The present invention relates to a device and method for loading pellets, such as catalyst pellets, into chemical reactor tubes, and more specifically to a loading sleeve that can be used in low clearance areas of a chemical reactor, where the length of the sleeve is greater than the clearance above the upper tube sheet.
Many chemical reactions are carried out in a shell and tube heat exchanger having a large number of vertically oriented chemical reactor tubes which are welded or expanded onto a plurality of horizontal tube sheets. One tube sheet is generally located near the top of the reactor, with the reactor tubes extending downwardly from it. Additional tube sheets may be located near the bottom or middle of the tubes. The reactor tubes often are loaded with catalyst pellets, which assist in the chemical reaction. Other types of pellets may be loaded into the tubes as well, such as inert pellets. In order for the reactor to perform optimally, it usually is desirable to distribute the catalyst pellets evenly in the tubes.
It is desirable to load the pellets into the reactor tubes at a controlled rate to eliminate bridging and to ensure uniform packing of the pellets within the tubes of the reactor vessel. Ideally, this controlled rate is such that the number of pellets simultaneously passing through any point is fewer than the number of pellets required to form a bridge. The rate usually is controlled by controlling the size of the opening through which the pellets pass into the reactor tube.
Sometimes, long loading sleeves are used as loading aids so that, when the sleeve is filled and then is removed, the pellets settle to the desired height, leaving the desired empty space or outage between the top of the pellets and the top of the reactor tube. However, there may be height limitations within the reactor which prevent the use of long loading sleeves.